The primary goal of this research is to improve the level of quantitation available from current diagnostic ultrasound instruments. Specific objectives include the development of techniques and instrumentation for obtaining cardiac dimensions and volumes non-invasively. A method has been developed to permit the location of ultrasound beams of scan planes in three-dimensional space referenced to a coordinate system on the patient. This permits examination of the same point or cross-section during the course of a serial study. It also permits measurements to be made of distances between cardiac structures which can not be imaged in a single two-dimensional scan. Finally, the availability of position and orientation data from a series of 2-D scans makes it possible to develop three-dimensional reconstructions of the ventricles. Clinical evaluation of these techniques is proceeding.